African Americans' experiences with racial discrimination have been implicated in several types of mental and physical health pathology during the adolescent period, including substance use, psychological symptoms, and externalizing behaviors. These problems not only disrupt normative developmental processes during adolescence, but also contribute to race-based health disparities in adulthood for African Americans. However, methodological problems related to measurement of the timing, context, and content of racial discrimination experiences substantially limit the ability to understand the role of racial discrimination in the daily lives and overall health of African American youth. In order to improve measurement and to promote synergy between theory and psychometric instrumentation, this grant will develop and validate a quantitative measure of experienced racial discrimination for use in longitudinal substance use and public health research with African American adolescents. This measure will improve the current state of racial discrimination research with African American adolescents by: 1) utilizing daily diary measurement to minimize retrospective bias; 2) including an array of contexts common in the lives of African American adolescents (e.g., school, internet, athletics); and 3) incorporating a mixed-method approach to validating the content of the measure. In this way, the proposed research project will take an innovative multidimensional, comprehensive, and mixed-method approach to developing a daily measure of experienced racial discrimination for use with African American adolescents. The ultimate goal of the current research and training fellowship application is to prepare the applicant to become an independent researcher with expertise in the field of experienced racial discrimination and health disparities for African American youth. The specific goals of this fellowship are: 1) to expand the applicant's knowledge of the experience of racial discrimination for African American adolescents; 2) to increase the applicant's skills in psychometric measure development; and 3) to educate the applicant in advanced quantitative analysis. The applicant will achieve these goals by engaging in multidisciplinary coursework, professional collaboration and mentorship, and research conferences and publications. These activities will enable the applicant to execute his fellowship and dissertation research aims of developing, validating, and disseminating a measure of experienced racial discrimination for use in daily, longitudinal substance use and public health research with African American adolescents.